High voltage Metal Oxide Semiconductor (MOS) transistors often rely upon a drift region that extends from a drain contact to a channel of a Field Effect Transistor (FET). The drift region typically has a much lower impurity concentration then an adjacent drain area, and the drift region connects the transistor's gate region with the adjacent drain area. The sustaining breakdown voltage of a MOS transistor often depends greatly on the concentration of the impurity in the drift region.